It was a year ago this month that Kate Hudson kicked off her relationship with Alex Rodriguez, which survived seven months and one World Series championship before fouling out in December. Now, she's supposedly fuming over the New York Yankees star's seemingly hot-and-heavy romance with Cameron Diaz.

Or so claim the tabs, which believe the actresses are "at war" (per OK!) and involved in a "fiery feud" (per Us Weekly) over the slugger.

Let's start with OK!, which is convinced that Hudson, who may or may not have recently boosted her bustline (and who may or may not have done it as a result of the breakup), wants another chance at bat with Rodriguez.

Oh, and she's said to be feeling "humiliated" that he rebounded with Cam, with one source overselling to the tab, "It was like a knife through her heart."

(That seems like an excessive reaction to a guy rumored to have portraits of himself as a centaur hanging above his bed, but moving on ...)

Us Weekly, meanwhile, goes the revenge route, speculating that Diaz hooked up with A-Rod as "a form of retaliation" because of Hudson's alleged interlude with Justin Timberlake soon after he and Cam pulled the plug on their four-year romance in early 2007.

"Kate thinks it's payback, pure and simple," opines an insider.

Counters a Diaz confidant, "Cameron was actually in a serious long-term relationship with Justin. She thinks it's a joke Kate would be mad. Kate is only upset because she hates being single."

Us also wonders if the purported "catfight" has spilled over into the professional arena, with the two eyeing the same big-screen roles.

"Kate thinks Cameron is an aging old lady actress struggling to remain sexy and relevant," snipes a source.

For those keeping score, Hudson is 31 and Diaz is 37. Your guess is as good as ours as to what age they appear to be acting.

Either way, Cameron, much like Kate, seems flexible about working around her squeeze's busy baseball schedule.

After a recent rendezvous in New York, during which the leggy A-lister reportedly made sure the baseballer spent time with her galpals Drew Barrymore and Kate Winslet (she was also snapped exiting his apartment building with an armful of overnight bags), she winged to Boston last weekend while his team took on the Red Sox.

"They arrived in Boston together via private jet and were whisked to the hotel," a source details to People.

They made a beeline for a luxury rooftop suite, where they hunkered down together and ordered "lots of room service" instead of venturing out.

The "super-athletic" and "goofy" pair, who first connected during a dance floor grinding session at a Super Bowl party in Miami back in February, "had an incredible time together," relays the snitch.

But was that "incredible time" due in part to Diaz's absence from the stands of Fenway Park? There's talk that A-Rod doesn't want Cameron to cheer him on from front and center seats, a la Hudson.

"Kate was at every New York game and then some and even went to Alex's game practice. Things got too clingy too fast," asserts a mole (via the New York Daily News). "Cameron is not really into baseball, so she wouldn't want to go to all the games."